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Diffstat (limited to 'fs/iomap/direct-io.c')
-rw-r--r--fs/iomap/direct-io.c29
1 files changed, 26 insertions, 3 deletions
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 811c898125a5..b4dc51063d36 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -31,6 +31,7 @@ struct iomap_dio {
atomic_t ref;
unsigned flags;
int error;
+ size_t done_before;
bool wait_for_completion;
union {
@@ -114,6 +115,9 @@ ssize_t iomap_dio_complete(struct iomap_dio *dio)
if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
ret = generic_write_sync(iocb, ret);
+ if (ret > 0)
+ ret += dio->done_before;
+
kfree(dio);
return ret;
@@ -375,6 +379,8 @@ static loff_t iomap_dio_hole_iter(const struct iomap_iter *iter,
loff_t length = iov_iter_zero(iomap_length(iter), dio->submit.iter);
dio->size += length;
+ if (!length)
+ return -EFAULT;
return length;
}
@@ -406,6 +412,8 @@ static loff_t iomap_dio_inline_iter(const struct iomap_iter *iomi,
copied = copy_to_iter(inline_data, length, iter);
}
dio->size += copied;
+ if (!copied)
+ return -EFAULT;
return copied;
}
@@ -450,13 +458,21 @@ static loff_t iomap_dio_iter(const struct iomap_iter *iter,
* may be pure data writes. In that case, we still need to do a full data sync
* completion.
*
+ * When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL,
+ * __iomap_dio_rw can return a partial result if it encounters a non-resident
+ * page in @iter after preparing a transfer. In that case, the non-resident
+ * pages can be faulted in and the request resumed with @done_before set to the
+ * number of bytes previously transferred. The request will then complete with
+ * the correct total number of bytes transferred; this is essential for
+ * completing partial requests asynchronously.
+ *
* Returns -ENOTBLK In case of a page invalidation invalidation failure for
* writes. The callers needs to fall back to buffered I/O in this case.
*/
struct iomap_dio *
__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
- unsigned int dio_flags)
+ unsigned int dio_flags, size_t done_before)
{
struct address_space *mapping = iocb->ki_filp->f_mapping;
struct inode *inode = file_inode(iocb->ki_filp);
@@ -486,6 +502,7 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
dio->dops = dops;
dio->error = 0;
dio->flags = 0;
+ dio->done_before = done_before;
dio->submit.iter = iter;
dio->submit.waiter = current;
@@ -587,6 +604,12 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size)
iov_iter_revert(iter, iomi.pos - dio->i_size);
+ if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) {
+ if (!(iocb->ki_flags & IOCB_NOWAIT))
+ wait_for_completion = true;
+ ret = 0;
+ }
+
/* magic error code to fall back to buffered I/O */
if (ret == -ENOTBLK) {
wait_for_completion = true;
@@ -649,11 +672,11 @@ EXPORT_SYMBOL_GPL(__iomap_dio_rw);
ssize_t
iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
- unsigned int dio_flags)
+ unsigned int dio_flags, size_t done_before)
{
struct iomap_dio *dio;
- dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags);
+ dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, done_before);
if (IS_ERR_OR_NULL(dio))
return PTR_ERR_OR_ZERO(dio);
return iomap_dio_complete(dio);